This article from Wired does a nice job of summarising current approaches to AI, particularly the use of algorithms and mimicry to establish effective patterns of behaviour…

AI researchers began to devise a raft of new techniques that were decidedly not modeled on human intelligence. By using probability-based algorithms to derive meaning from huge amounts of data, researchers discovered that they didn’t need to teach a computer how to accomplish a task; they could just show it what people did and let the machine figure out how to emulate that behavior under similar circumstances. They used genetic algorithms, which comb through randomly generated chunks of code, skim the highest-performing ones, and splice them together to spawn new code. As the process is repeated, the evolved programs become amazingly effective, often comparable to the output of the most experienced coders.